The use of Raman spectroscopy to identify and characterize transitional cell carcinoma in vitro

OBJECTIVE

To determine whether Raman spectroscopy can be used to differentiate between normal, inflammatory and malignant bladder pathologies in vitro, and secondly if it can used to grade and stage transitional cell carcinoma (TCC).

MATERIALS AND METHODS

In all, 1525 Raman spectra were measured from 75 bladder samples comprising normal bladder, cystitis, carcinoma in situ (CIS), TCC and adenocarcinoma. Multivariate analysis was applied to the spectral dataset to construct diagnostic algorithms; these were then tested for their ability to determine the histological diagnosis of each sample from its Raman spectrum.

RESULTS

The diagnostic algorithms could be used to accurately differentiate among the pathological groups, in particular, a three-group algorithm differentiated among normal bladder, cystitis and TCC/CIS with sensitivities and specificities of > 90%. Algorithms could also accurately characterize TCC in terms of splitting them into low (G1/G2) or high (G3) grade and superficial (pTa) or invasive (pT1/pT2) stage.

CONCLUSION

Raman spectroscopy can be used to accurately identify and grade/stage TCC in vitro. The technique therefore shows promise for use as an objective method to assist the pathologist in assessing bladder pathologies. Raman spectroscopy also has potential to provide immediate pathological diagnoses during surgical procedures. Following the promising results of this in vitro study, in vivo cystoscopic studies are planned.

Managing heart failure with immunomodulatory agents

The evidence in favor of immune activation as an operative mechanism that contributes to the progression of heart failure continues to accumulate. Indeed, a number of clinical trials have demonstrated the clinical interest of interventions in this area for many years, but none have proven useful. The only trial ever conducted to define the effect of immunotherapy in mortality, however, is the one currently ongoing using Etanercept in patients with symptomatic heart failure. Irrespective of the final outcome of the study, the growing interest in inflammation as a contributory pathway in disease progression has now opened the field to develop new strategies for intervention. Whether specific or non-specific therapies may prove useful will be defined only by the results of randomized clinical trials.

Cardiac hypertrophy after transplantation is associated with persistent expression of tumor necrosis factor-alpha

BACKGROUND

The mechanisms that contribute to cardiac allograft hypertrophy are not known; however, the rapid progression and severity of hypertrophy suggest that nonhemodynamic factors may play a contributory role. Tumor necrosis factor-alpha (TNF-alpha) is a cytokine produced in cardiac allografts and capable of producing hypertrophy and fibrosis; therefore, we suggest that TNF-alpha may play a contributory role. Accordingly, the aims of our study were to define the role of systemic hypertension in the development of hypertrophy, characterize the histological determinants of hypertrophy, and characterize the expression of myocardial TNF-alpha after heart transplantation.

METHODS AND RESULTS

To separate the effect of hypertension from immune injury in the development of cardiac allograft hypertrophy, we measured the gain in left ventricular mass by 2D echocardiography in heart transplant recipients and lung transplant recipients who developed similar rates of systemic hypertension. The gain in left ventricular mass was 73% in heart transplant recipients and 7% in lung transplant recipients (P<0.0001). By comparing myocardial samples obtained during the first week after transplant and at 1 year, we found that there was a significant increase in total collagen content (P<0.0001), collagen I (P<0.0001), collagen III (P<0.0001), and myocyte size (P<0.0001). These changes were associated with persistent myocardial TNF-alpha expression.

CONCLUSIONS

We suggest that the contribution of hypertension to cardiac allograft hypertrophy is minimal and that persistent intracardiac expression of TNF-alpha may contribute to the development of cardiac allograft hypertrophy.

Pleiotropic effects of statins: do they matter?

Treatment with the 3-hydroxy-3-methylglutaryl coenyzme A reductase inhibitors (or statins) reduces the risk for cardiovascular events across a broad spectrum of patient profiles, as evidenced by both primary prevention and secondary prevention trials. Improved survival by way of reduced deaths from coronary heart disease was also reported with these agents, which are primarily indicated for substantial reduction in LDL-cholesterol levels. However, the statins are extremely complex drugs and exhibit a wide variety of vascular effects that may or may not be dependent on their lipid-modifying properties. These so-called pleiotropic effects include alterations of endothelial function, inflammation, coagulation, and plaque stability. The relative contribution of the nonlipid effects of statin therapy to the well-documented clinical benefits is currently under intense investigation.

The renin angiotensin system as a risk factor for coronary artery disease

The renin angiotensin system was demonstrated to play a significant role in the genesis of hypertension and regulation of vascular tone over 100 years ago. The early investigations were subsequently expanded to implicate the renin angiotensin system in a variety of physiologic processes that may play a significant role in the initiation and progression of atherosclerosis. The renin angiotensin system modulates vascular structure and left ventricular hypertrophy via a number of trophic effects. Elevated levels of angiotensin II are associated with the generation of oxidative stress, and may thus play a significant role in the earliest phases of atherosclerosis. The role inflammation plays in atherosclerosis is amplified by the renin angiotensin system via the effects on adhesion molecules, growth factors, and chemoattractant molecules, which modulate the migration of inflammatory cells into the subendothelial space. The effects of angiotensin II, which may be at least partially genetically mediated, have been implicated in epidemiologic and clinical studies as a risk factor for the development of atherosclerosis. This review centers on the potential role that the renin angiotensin system plays as a risk factor for the development of atherosclerosis, and the role of converting enzyme inhibition or angiotensin receptor blockade as a mechanism to decrease the initiation, progression, and clinical consequences of the atherosclerotic process.

Pharmacokinetics and safety of an anti-vascular endothelial growth factor aptamer (NX1838) following injection into the vitreous humor of rhesus monkeys

PURPOSE

The objective of this study was to determine the pharmacokinetics and safety for NX1838 following injection into the vitreous humor of rhesus monkeys.

METHODS

Plasma and vitreous humor pharmacokinetics were determined following a single bilateral 0.25, 0.50, 1.0, 1.5, or 2.0 mg/eye dose. In addition, the pharmacokinetics and toxicological properties of NX1838 were determined following six biweekly bilateral injections of 0.25 or 0.50 mg/eye or following four biweekly bilateral injections of 0.10 mg per eye followed by two biweekly bilateral injections of 1.0 mg per eye.

RESULTS

Plasma and vitreous humor NX1838 concentrations were linearly related to the dose administered. NX1838 was cleared intact from the vitreous humor into the plasma with a half-life of approximately 94 h, which was in agreement with the plasma terminal half-life. Vascular endothelial growth factor (VEGF)-binding assays demonstrated that the NX1838 remaining in the vitreous humor after 28 days was fully active. No toxicological effects or antibody responses were evident.

CONCLUSIONS

The no observable effect level was greater than six biweekly bilateral 0.50 mg/eye doses or two biweekly bilateral 1.0 mg/eye doses. These pharmacokinetic and safety data support monthly 1 or 2 mg/eye dose regimens in human clinical trials.

The implications for cardiac recovery of left ventricular assist device support on myocardial collagen content

BACKGROUND

To define the beneficial cellular changes that occur with chronic ventricular unloading, we determined the effect of left ventricular assist device (LVAD) placement on myocardial fibrosis.

METHODS

We obtained paired myocardial samples (before and after LVAD implantation) from 10 patients (aged 43 to 64 years) with end-stage cardiomyopathy. We first determined regional collagen expression of an explanted heart by a computerized semiquantitative analysis of positive picro-sirius red stained areas.

RESULTS

We found that there was no statistically significant difference in collagen content between regions of the failed heart studied. Next we determined collagen content in these paired myocardial biopsies pre- and post-LVAD implantation. All 10 patients had significant reductions in collagen content after LVAD placement with a mean reduction of 82% (percent of tissue area stained decreased from 32% +/- 4% to 4% +/- 0.8%, P < 0.001).

CONCLUSION

In summary, these data demonstrate that chronic mechanical circulatory support significantly reduces fibrosis in the failing myocardium.

Comparative tolerability of the HMG-CoA reductase inhibitors

The availability of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has revolutionised the treatment of lipid abnormalities in patients at risk for the development of coronary atherosclerosis. The relatively widespread experience with HMG-CoA therapy has allowed a clear picture to emerge concerning the relative tolerability of these agents. While HMG-CoA reductase inhibitors have been shown to decrease complications from atherosclerosis and to improve total mortality, concern has been raised as to the long term safety of these agents. They came under close scrutiny in early trials because ocular complications had been seen with older inhibitors of cholesterol synthesis. However, extensive evaluation demonstrated no significant adverse alteration of ophthalmological function by the HMG-CoA reductase inhibitors. Extensive experience with the potential adverse effect of the HMG-CoA reductase inhibitors on hepatic function has accumulated. The effect on hepatic function for the various HMG-CoA reductase inhibitors is roughly dose-related and 1 to 3% of patients experience an increase in hepatic enzyme levels. The majority of liver abnormalities occur within the first 3 months of therapy and require monitoring. Rhabdomyolysis is an uncommon syndrome and occurs in approximately 0.1% of patients who receive HMG-CoA reductase inhibitor monotherapy. However, the incidence is increased when HMG-CoA reductase inhibitors are used in combination with agents that share a common metabolic path. The role of the cytochrome P450 (CYP) enzyme system in drug-drug interactions involving HMG-CoA reductase inhibitors has been extensively studied. Atorvastatin, cerivastatin, lovastatin and simvastatin are predominantly metabolised by the CYP3A4 isozyme. Fluvastatin has several metabolic pathways which involve the CYP enzyme system. Pravastatin is not significantly metabolised by this enzyme and thus has theoretical advantage in combination therapy. The major interactions with HMG-CoA reductase inhibitors in combination therapy involving rhabdomyolysis include fibric acid derivatives, erythromycin, cyclosporin and fluconazole. Additional concern has been raised relative to overzealous lowering of cholesterol which could occur due to the potency of therapy with these agents. Currently, there is no evidence from clinical trials of an increase in cardiovascular or total mortality associated with potent low density lipoprotein reduction. However, a threshold effect had been inferred by retrospective analysis of the Cholesterol and Recurrent Events study utilising pravastatin and the role of aggressive lipid therapy is currently being addressed in several large scale trials.

Pleiotropic effects of statins

The advent of statin therapy has revolutionized the ability of the clinician to manage patients at risk for the development of an ischemic event due to dyslipidemia. Large-scale clinical trials involving thousands of patients in both primary and secondary prevention have clearly demonstrated that statin therapy will reduce cardiovascular mortality across a broad spectrum of patient subgroups. Additionally, in adequately powered trials, total mortality has been successfully decreased by the use of statin therapy. However, the precise mechanism underlying the benefit of statin therapy has been controversial due to the multiplicity of potential benefits that statins have demonstrated in addition to pure lipid lowering. The causal theory of pharmacologic benefit reiterates the lipid hypothesis, which states that dyslipidemia is central to the process of atherosclerosis and the clinical benefit which accrues from statin therapy is a function of the degree of lipid lowering. The noncausal theory supports the premise that clinical benefits are related primarily to pleiotropic effects of statins (endothelial function, inflammation, coagulation and plaque vulnerability) as being the major modulators of clinical benefit. This review will focus on the potential beneficial effects of statin therapy on a number of the pleiotropic effects of statins and the potential role that these activities play in the reduction of risk for ischemic events.

Renin angiotensin system and ASCVD

The renin angiotensin system was first described over 100 years ago and is still the focus of intense clinical and basic science investigation. The renin angiotensin system was demonstrated to play a major pathogenetic role in hypertension. The development of inhibitors of angiotensin-converting enzyme and specific receptor blockers for angiotensin-II represent a major advance in the treatment of elevated blood pressure. However, the renin angiotensin system is intimately involved in a number of conditions that increase the risk for atherosclerosis. Components of the renin angiotensin system have demonstrated to play a significant role in the initial phases of atherosclerosis. Additionally, plaque vulnerability and the potential for an acute atherosclerotic event are also modulated by the renin angiotensin system. Angiotensin-II plays a significant role in the balance between intravascular clot formation and fibrinolytic potential. Therefore, blocking the generation of angiotensin-II or inhibiting its binding to specific receptors may decrease the subsequent risk for unstable angina and acute myocardial infarction. Increased renin activity has been correlated as a statistical risk factor for coronary heart disease and converting enzyme inhibition has been demonstrated to decrease the incidence of acute ischemic events. This review will center on the role of modulation of the renin angiotensin system as a means to alter the clinical course of coronary atherosclerosis.

Role of tumour necrosis factor-alpha in the progression of heart failure: therapeutic implications

The experimental and clinical evidence that demonstrates the effect of various cytokines, and in particular tumour necrosis factor (TNF)alpha, in patients with heart failure continues to accumulate. It is well established that increased levels of TNFalpha appear in the circulation of patients with heart failure and that the levels may have prognostic significance. Also, increased circulating TNFalpha levels may be responsible for the decreased expression of myocardial TNF receptors observed in failing myocardium. Along with these clinical data, it has been clearly demonstrated that increased levels of TNFalpha lead to cardiomyopathy and eventually death in experimental animals. Therefore, it is reasonable to assume that the increased levels of TNFalpha in patients with heart failure may be detrimental to cardiac function. The hypothesis that TNFalpha contributes to the pathogenesis of heart failure has recently been tested at the clinical level. The results of specific TNFalpha antagonism in patients with symptomatic heart failure demonstrate that anti-TNFalpha therapy is well tolerated and may be effective. This hypothesis is currently being tested in a large randomised, multicentre study that is expected to be complete within the next 2 years. Perhaps the most important aspect of the evolving research into the role of cytokines in heart failure is that the recognition of activation of inflammatory mediators provides new targets for therapeutic intervention.

Detection and plasma pharmacokinetics of an anti-vascular endothelial growth factor oligonucleotide-aptamer (NX1838) in rhesus monkeys

Aptamers are oligonucleotide ligands selected, in vitro, to bind a specified target protein. The first aptamer to reach human clinical testing is NX1838, a polyethylene glycol conjugated aptamer that inhibits vascular endothelial growth factor. This paper describes the validation of a high-performance liquid chromatographic anion-exchange method for the determination of NX1838 in plasma. Measurements of intact NX1838 had a coefficient of variation of less than 8% and an accuracy between 107% and 115%. The assay was utilized to determine NX1838 plasma pharmacokinetics in rhesus monkeys following a single 1 mg/kg intravenous or subcutaneous dose. Following intravenous administration, the maximum achieved plasma concentration was 25.5 microg/ml with a terminal half-life of 9.3 h and clearance rate of 6.2 ml/h. After subcutaneous administration, the fraction of the dose absorbed into the plasma compartment was 0.78 with a time to peak concentration (4.9 microg/ml) of 8 to 12 h.

Influence of low HDL on progression of coronary artery disease and response to fluvastatin therapy

BACKGROUND--Patients with coronary artery disease (CAD) commonly have low HDL cholesterol (HDL-C) and mildly elevated LDL cholesterol (LDL-C), leading to uncertainty as to whether the appropriate goal of therapy should be lowering LDL-C or raising HDL-C. METHODS AND RESULTS--Patients in the Lipoprotein and Coronary Atherosclerosis Study (LCAS) had mildly to moderately elevated LDL-C; many also had low HDL-C, providing an opportunity to compare angiographic progression and the benefits of the HMG-CoA reductase inhibitor fluvastatin in patients with low versus patients with higher HDL-C. Of the 339 patients with biochemical and angiographic data, 68 had baseline HDL-C <0.91 mmol/L (35 mg/dL), mean 0.82+/-0.06 mmol/L (31. 7+/-2.2 mg/dL), versus 1.23+/-0.29 mmol/L (47.4+/-11.2 mg/dL) in patients with baseline HDL-C >/=0.91 mmol/L. Among patients on placebo, those with low HDL-C had significantly more angiographic progression than those with higher HDL-C. Fluvastatin significantly reduced progression among low-HDL-C patients: 0.065+/-0.036 mm versus 0.274+/-0.045 mm in placebo patients (P=0.0004); respective minimum lumen diameter decreases among higher-HDL-C patients were 0. 036+/-0.021 mm and 0.083+/-0.019 mm (P=0.09). The treatment effect of fluvastatin on minimum lumen diameter change was significantly greater among low-HDL-C patients than among higher-HDL-C patients (P=0.01); among low-HDL-C patients, fluvastatin patients had improved event-free survival compared with placebo patients. CONCLUSIONS--Although the predominant lipid-modifying effect of fluvastatin is to decrease LDL-C, patients with low HDL-C received the greatest angiographic and clinical benefit.

Intensive medical therapy versus coronary angioplasty for suppression of myocardial ischemia in survivors of acute myocardial infarction: a prospective, randomized pilot study

BACKGROUND

Patients who have inducible ischemia after acute myocardial infarction (AMI) generally undergo coronary angiography with the intent to revascularize. Whether this approach is superior to intensive treatment with anti-ischemic medications is unknown.

METHODS AND RESULTS

We performed a prospective, randomized pilot study comparing intensive medical therapy with coronary angioplasty (PTCA) for suppression of myocardial ischemia in 44 stable survivors of AMI. Myocardial ischemia was quantified with adenosine 201Tl tomography (SPECT) performed 4.5+/-2.9 days after AMI. All patients at baseline had a large total (>/=20%) and ischemic (>/=10%) left ventricular perfusion defect size (PDS). SPECT was repeated at 43+/-26 days after therapy was optimized. The total stress-induced PDS was comparably reduced with medical therapy (from 38+/-13% to 26+/-16%; P<0.0001) and PTCA (from 35+/-12% to 20+/-16%; P<0.0001). The reduction in ischemic PDS was also similar (P=NS) in both groups. Cardiac events occurred in 7 of 44 patients over 12+/-5 months. Patients who remained clinically stable had a greater reduction in ischemic PDS (-13+/-9%) than those who had a recurrent cardiac event (-5+/-7%; P<0.02). Event-free survival was superior in the 24 patients who had a significant (>/=9%) reduction in PDS (96%) compared with those who did not (65%; P=0.009).

CONCLUSIONS

In this small pilot study, intensive medical therapy and PTCA were comparable at suppressing ischemia in stable patients after AMI. Sequential imaging with adenosine SPECT can track changes in PDS after anti-ischemic therapies and thereby predict subsequent outcome. Corroboration of these preliminary findings in a larger cardiac-event trial is warranted.

Economic implications of lipid-lowering trials: current considerations in selecting a statin

Little doubt remains about the value of lipid-lowering therapy since publication of the results of large, randomized, controlled trials that show decreased total, as well as coronary, mortality with the use of statins for primary and secondary prevention of coronary artery disease. All of the available statins are effective and safe, but they vary greatly in terms of cost-effectiveness. Fluvastatin has been determined to be a cost-effective therapeutic agent in the large proportion of the population with mild-to-moderate dyslipidemia who fit treatment guidelines of the National Cholesterol Education Program (NCEP). Atorvastatin and simvastatin are cost-effective for the relatively smaller number of patients who require greater reductions in cholesterol.

Aggressive lipid therapy in the statin era

Aggressive cholesterol lowering with 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor (statin) therapy has contributed to the substantial decrease in coronary heart disease (CHD) morbidity and mortality in recent years, as documented in a number of controlled clinical trials in both primary- and secondary-prevention patients. Although benefit was first established in patients with severe hypercholesterolemia, more recent trials have extended the benefit to patients with mildly to moderately elevated cholesterol. In addition to improvements on the lipid profile, statins appear to confer nonlipid benefits, such as improved endothelial function, modification of plaque cellularity, and plaque stabilization.

Progressive deterioration of coronary flow reserve after heart transplantation

BACKGROUND

The purpose of this study was to determine coronary flow reserve in cardiac allograft recipients early (0 to 3 years) and late (3 to 7 years) after heart transplantation.

METHODS AND RESULTS

With the use of a Doppler tipped guide wire, coronary flow reserve (ratio of hyperemic to baseline coronary flow velocity) was measured in 82 patients before and after intracoronary adenosine. Forty-five patients were early (< or =3 years) after transplantation, 24 were late, and 13 were control patients with single-vessel coronary artery disease. Coronary flow reserve in the early transplantation patients was similar to that in the control group (2.9+/-0.2 vs 3.0 +/-0.6, p=not significant) but was reduced in the late transplantation group (2.2+/-0.5 vs 3.0+/-0.6, p < 0.001). There were differences in coronary flow reserve between the early and late transplantation patient groups (3.0+/-0.6 vs 2.2+/-0.5, p < 0.001 ) despite equally elevated mean arterial pressure, mean heart rate, mean pulmonary capillary wedge pressure, and mean left ventricular mass in the two groups. Coronary flow reserve in patients with angiographic allograft arteriopathy (n=19) was reduced when compared with coronary flow reserve of patients with normal vessels (n=50) (1.9+/-0.3 vs 3.1+/-0.6, p < 0.001).

CONCLUSIONS

There is progressive deterioration of coronary flow reserve over time after transplantation. Dysfunction of the coronary microcirculation rather than determinants of myocardial oxygen consumption contributes to this reduction.

Effects of lipid lowering therapy on progression of coronary and carotid artery disease

Recent data have extended the benefit of lipid lowering therapy to patients with only mildly to moderately elevated LDL-cholesterol, which is typical of patients with coronary artery disease. Meta-analysis of clinical trials of statin therapy with similar sample sizes indicated that the LDL-cholesterol level on treatment was as good a predictor of angiographic benefit as was the percentage reduction in LDL-cholesterol. We review evidence that management of triglyceride-rich lipoproteins, HDL, fibrinogen, lipoprotein particle size, LDL-oxidation, and lipoprotein (a) may also favorably influence atherosclerotic progression. Angiographic and arterial ultrasound trials of lipid lowering therapy have demonstrated benefits on disease progression that are consistent with benefits on myocardial infarction, stroke, and death reported in larger, lengthier trials.

Effects of fluvastatin on coronary atherosclerosis in patients with mild to moderate cholesterol elevations (Lipoprotein and Coronary Atherosclerosis Study [LCAS])

Despite the potential for reduced morbidity and mortality, aggressive intervention against mild to moderate hypercholesterolemia in patients with coronary heart disease (CHD) remains controversial and infrequently practiced. Eligible patients in the 2.5-year Lipoprotein and Coronary Atherosclerosis Study were men and women aged 35 to 75 years with angiographic CHD and mean low-density lipoprotein (LDL) cholesterol of 115 to 190 mg/dl despite diet. Patients (n = 429; 19% women) were randomized to fluvastatin 20 mg twice daily or placebo. One fourth of patients were also assigned open-label adjunctive cholestyramine up to 12 g/day because prerandomization LDL cholesterol remained > or = 160 mg/dl. The primary end point, assessed by quantitative coronary angiography, was within-patient per-lesion change in minimum lumen diameter (MLD) of qualifying lesions. Across 2.5 years, mean LDL cholesterol was reduced by 23.9% in all fluvastatin patients (+/- cholestyramine) (146 to 111 mg/dl) and by 22.5% in the fluvastatin only subgroup (137 to 106 mg/dl). Primary end point analysis (340 patients) showed significantly less lesion progression in all fluvastatin versus all placebo patients, deltaMLD -0.028 versus -0.100 mm (p <0.01), and for fluvastatin alone versus placebo alone, deltaMLD -0.024 versus -0.094 mm (p <0.02). A consistent angiographic benefit with treatment was seen whether baseline LDL cholesterol was above or below 160 or 130 mg/dl. Beneficial trends with treatment were also consistently seen in clinical event rates but were not statistically significant. Thus, lipid lowering by fluvastatin in patients with mildly to moderately elevated LDL cholesterol significantly slowed CHD progression.

Association of angiotensin I-converting enzyme gene polymorphism with myocardial ischemia and patency of infarct-related artery in patients with acute myocardial infarction

OBJECTIVES

We determined the influence of angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism on the extent of myocardial ischemia in patients with acute myocardial infarction.

BACKGROUND

The I/D polymorphism, which in part controls plasma and tissue expression of ACE, has been implicated in predisposition to myocardial infarction and ventricular remodeling.

METHODS

I/D genotyping, predischarge adenosine-thallium-201 perfusion tomography and radionuclide angiography were performed in 113 patients (72 men, 41 women) with a diagnosis of acute myocardial infarction. A subgroup of 96 patients also underwent coronary angiography.

RESULTS

Genotypes DD, ID and II were present in 27, 56 and 30 patients, respectively. There was no significant difference in the baseline characteristics of patients, total creatine kinase, peak MB fraction, Killip class, mean ejection fraction or the number of diseased vessels in patients with the DD, ID or II genotype. However, the size of the total and the reversible perfusion defects was greater in those with DD than in those with ID or II genotype (total defect size [mean +/- SD] 33.7 +/- 22.5%, 29.5 +/- 19.2% and 22.2 +/- 16.0%, respectively [p = 0.022]; reversible defect size 18.0 +/- 16.0%, 12.1 +/- 11.6% and 8.2 +/- 7.8%, respectively [p = 0.006]). Occlusion of the infarct-related artery was also more common in patients with DD genotype (odds ratio 3.9, 95% confidence interval 1.4 to 11.0). Multivariate analysis showed that the I/D genotype was an independent predictor of perfusion defect size and patency of the infarct-related artery (p = 0.001).

CONCLUSIONS

DD genotype was associated with a larger ischemic defect and occlusion of the infarct-related artery. Patients with DD genotype, having a larger ischemic defect, are expected to be at a greater risk for subsequent cardiovascular events.

Endocarditis

Endocarditis remains a major worldwide problem despite significant advances in diagnostic and therapeutic interventions. This review centers on the recent studies that have been published in the past year concerning the epidemiologic, diagnostic, and therapeutic aspects of infective and noninfective endocarditis in both the general and special high-risk populations (eg, drug users, HIV-infected patients, and elderly patients).

Choosing the right lipid-regulating agent. A guide to selection

If dietary therapy and other lifestyle changes do not adequately normalise blood lipid levels, lipid-regulating drugs, as single-drug or combination-drug therapy, may be prescribed to supplement lifestyle changes. Evaluation of the individual patient's health and risk status, determination of the dyslipidaemia, definition of treatment goals and a clear understanding of the mechanisms and effects of lipid-regulating agents are necessary for optimisation of treatment. Although all the available lipid-regulating agents lower low density lipoprotein (LDL) cholesterol, the agents with the greatest LDL cholesterol-lowering effect are the bile acid sequestrants, which up-regulate the LDL receptor by the decrease in intrahepatic cholesterol caused by the interruption of enterohepatic circulation of cholesterol-rich bile acids, and the HMG-CoA reductase inhibitors, which partially inhibit HMG-CoA reductase. The agents with the greatest triglyceride-lowering effect are nicotinic acid, which decreases the production of very low density lipoprotein (VLDL) cholesterol and reduces the availability of free fatty acids in the circulation, and the fibric acid derivatives, which increase lipoprotein lipase activity and may also decrease the release of free fatty acids. Although the safety profile of the available lipid-regulating drugs has been established, patients should be monitored for potential adverse effects and interactions with concomitantly administered agents. When used correctly, lipid-regulating drug therapy is highly effective in the treatment of a variety of dyslipidaemias.

Effect of gemfibrozil on levels of lipoprotein[a] in type II hyperlipoproteinemic subjects

Plasma lipoprotein[a] (Lp[a]) levels are highly correlated with angiographically demonstrable coronary heart disease, and elevated Lp[a] is an independent risk factor for atherosclerosis. Previous studies have provided evidence that the levels of Lp[a] and triglyceride are related, suggesting that Lp[a] might be altered by gemfibrozil, a drug well known for its efficacy in reducing plasma triglycerides. Accordingly, 18 type IIa and 16 type IIb hyperlipoproteinemic males aged 35-58 were treated for 3 months with 600 mg of gemfibrozil twice daily. The efficacy of the drug in altering lipid and lipoprotein levels was different in the two type groups. In type IIa and IIb subjects the respective changes in median levels were: total cholesterol, -7.5 and -8.5% triglycerides, -35.6 and -54.4%; HDL-cholesterol, +9.0 and +11.0%; and Lp[a], -17.2 and +6.1%. Before and after gemfibrozil treatment, 7 type IIa and 10 type IIB subjects were given a 100 g/2 m2 oral-fat load; triglycerides and Lp[a] were measured post-prandially at 0, 2, 4, 6, 8, and 10 h. The differences between before- and after-gemfibrozil post-prandial curve integrated areas (PPCIA) were compared for triglycerides and Lp[a]. The changes in median PPCIA for triglycerides in types IIa and IIB were -54% and -53%, and for Lp[a] were -8% and +8%, respectively. These results indicate i) that the levels of Lp[a] are about 2 times higher in type IIa than IIb subjects, and ii) that although gemfibrozil elicits a rather uniform decrease in fasting and post-prandial triglyceride levels in type IIa and IIb patients, the drug causes heterogeneous changes in Lp[a], suggesting that different metabolic mechanisms may be dominant in subjects showing opposing effects.

Currently available hypolipidaemic drugs and future therapeutic developments

Dyslipidaemia may be treated with a number of safe and effective pharmacological agents that target specific lipid disorders through a variety of mechanisms. The bile-acid sequestrants--cholestyramine and colestipol--primarily decrease LDL cholesterol by binding bile acids, thereby decreasing intrahepatic cholesterol, and by increasing the activity of LDL receptors. Nicotinic acid lowers LDL cholesterol and triglyceride by decreasing VLDL synthesis and by decreasing free fatty acid mobilization from peripheral adipocytes. The HMG-CoA reductase inhibitors--fluvastatin, lovastatin, pravastatin and simvastatin--lower LDL cholesterol by partially inhibiting HMG-CoA reductase (the rate-limiting enzyme of cholesterol biosynthesis) and by increasing the activity of LDL receptors. The fibric-acid derivatives--bezafibrate, ciprofibrate, clofibrate, fenofibrate and gemfibrozil--primarily decrease triglyceride by increasing lipoprotein lipase activity and by decreasing the release of free fatty acids from peripheral adipose tissue. Probucol decreases LDL cholesterol by increasing non-receptor-mediated LDL clearance; as an anti-oxidant, probucol also decreases LDL oxidation; oxidized LDL which is thought to lead to atherogenesis. Although these agents have been proven safe in clinical trials, like any drug, they carry the risk for adverse effects. The bile-acid sequestrants may cause constipation, reflux oesophagitis, and dyspepsia, and may bind coadministered medications such as digitalis glycosides, beta blockers, warfarin, and exogenous thyroid hormone. Nicotinic acid use is commonly associated with flushing and pruritus and may also cause non-specific gastrointestinal complaints, hepatotoxicity (hepatic necrosis, hepatitis, or elevated liver enzymes), gout, myolysis, decreased glucose tolerance and increased fasting glucose levels, and ophthalmological complications including decreased visual acuity, toxic amblyopia, and cystic maculopathy. The HMG-CoA reductase inhibitors may produce liver enzyme elevations, creatine kinase elevations and rhabdomyolysis. The combination of a reductase inhibitor and a fibrate increases the risk for rhabdomyolysis. Possible adverse effects of the fibric-acid derivatives include abdominal discomfort, nausea, flatulence, increased lithogenicity of bile, liver enzyme elevations and creatine kinase elevations. Probucol may increase the QTc interval and may cause non-specific gastrointestinal complaints.

Clinical investigations of the arrest and reversal of coronary artery disease

Trials of lipid-lowering therapy with angiographically monitored endpoints have demonstrated that regression of atherosclerosis can be achieved. Additionally, the unexpected clinical benefit seen in some trials has suggested that stabilization of lesions may be even more important clinically than regression, and more readily achievable. However, much additional research is needed to clarify the effects of therapy on the heterogeneous population of lesions and the precise mechanisms by which such therapy influences event rates. It is nonetheless clear that aggressive lowering of LDL cholesterol is indicated in patients with established coronary disease, who are at high risk for future events. Accordingly, the new guidelines of the USA National Cholesterol Education Program (NCEP) have adopted an LDL cholesterol goal of less than 100 mg/dl (2.6 mmol/l) in patients with confirmed atherosclerotic disease. Ongoing and future strategies for investigating lipid-lowering therapy and the progression of atherosclerosis include new imaging modalities, such as ultrasonography of the carotid arteries and PET scanning, and use of more potent lipid-lowering interventions.

The educational implications of reproductive problems identified during investigations at Michigan dairy farms

This study constitutes the review of 44 dairy herd investigations that were initiated because of complaints relating to decreased reproductive efficiency. Each investigation was conducted at the request of the veterinary practitioner who provided the routine reproductive examinations and consultations at the farm. Thus the types of problems identified were those not resolved by routine veterinary care and management practices. A total of 4.5, 27.3 and 31.8% of the farms, respectively, failed to keep reproductive records, failed to maintain accurate records on events such as breeding dates, or failed to evaluate available summary reports with the local veterinary practitioner. Of the 44 farms, 50.0, 38.6, 54.5 and 11.4%, respectively, reported problems related to estrus detection rate, number of days to first service (for reasons other than estrus detection), conception rate and early embryonic death. Within each of these reproductive parameters specific problems were defined and discussed. Reproductive inefficiency was found to be most commonly associated with ineffective estrus detection and decreased conception rate. Most importantly, farm managers and employees frequently misunderstood the relationship between the accuracy of estrus detection and the conception rate (61.4% of the farms). We therefore identified factors which have an impact on dairy herd reproductive efficiency to suggest topics for training programs for producers and practicing veterinarians as well as for elective courses for veterinary students in the area of theriogenology.

Antihyperlipidaemic agents. Drug interactions of clinical significance

The available antihyperlipidaemic drugs are generally safe and effective, and major systemic adverse effects are uncommon. However, because of their complex mechanisms of action, careful monitoring is required to identify and correct potential drug interactions. Bile acid sequestrants are the most difficult of these agents to administer concomitantly, because their nonspecific binding results in decreased bioavailability of a number of other drugs, including thiazide diuretics, digitalis preparations, beta-blockers, coumarin anticoagulants, thyroid hormones, fibric acid derivatives and certain oral antihyperglycaemia agents. Although the incidence is low, nicotinic acid may cause hepatic necrosis and so should not be used with drugs that adversely affect hepatic structure or function. With the HMG-CoA reductase inhibitors, relatively new agents for which clinical data are still being accumulated, the major problems appears to be rhabdomyolysis, associated with the concomitant use of cyclosporin, fibric acid derivatives or erythromycin, and mild, intermittent hepatic abnormalities that may be potentiated by other hepatotoxic drugs. Fibrates also have the potential to cause rhabdomyolysis, although generally only in combination with HMG-CoA reductase inhibitors, and are subject to binding by concomitantly administered bile acid sequestrants. The major interaction involving probucol is a possible additive effect with drugs or clinical conditions that alter the prolongation of the QTc interval, increasing the potential for polymorphic ventricular tachycardia.

Comparative effects of simvastatin and lovastatin in patients with hypercholesterolemia. The Simvastatin and Lovastatin Multicenter Study Participants

The efficacy, safety profile, and tolerability of the HMG-CoA reductase inhibitors simvastatin and lovastatin were compared in a multicenter, randomized, double-blind study in patients with moderate hypercholesterolemia. Commonly prescribed doses of these two drugs were used by 544 men and women, who followed an American Heart Association phase I diet during a 6-week baseline period and for the 24 weeks of active treatment. Simvastatin 10 mg and lovastatin 20 mg produced statistically significant reductions in total and low-density lipoprotein cholesterol (LDL-C). Patients receiving simvastatin 10 mg once daily and lovastatin 20 mg once daily experienced similar reductions in LDL-C and total cholesterol; however, simvastatin 20 mg was statistically superior to lovastatin 40 mg in decreasing these lipid fractions. For all treatment groups, increases in high-density lipoprotein cholesterol were inversely related to baseline levels. Moderate decreases in triglycerides occurred with all doses. Lipoprotein(a) levels, measured in a subset of patients, were similar before and after treatment. Both drugs were well tolerated.

Hyperlipidemia after heart transplantation: report of a 6-year experience, with treatment recommendations

Mean plasma lipid values in 100 patients who survived greater than 3 months after heart transplantation increased significantly at 3 months over pretransplantation values: total cholesterol from 168 +/- 7 to 234 +/- 7 mg/dl, low density lipoprotein (LDL) cholesterol from 111 +/- 6 to 148 +/- 6 mg/dl, high density lipoprotein (HDL) cholesterol from 34 +/- 1 to 47 +/- 1 mg/dl and triglycerides from 107 +/- 6 to 195 +/- 10 mg/dl. There were no significant increases after this time. The LDL cholesterol values reamined greater than or equal to 130 mg/dl in 64% of patients and triglyceride values remained greater than or equal to 200 mg/dl in 41% of patients 6 months after postoperative dietary instructions. Beginning in 1985, select patients whose total cholesterol values remained greater than 300 mg/dl despite 6 months of dietary intervention were treated with lovastatin given alone in a high dose (40 to 80 mg/day) or in combination with another hypolipidemic agent. Four of the five patients so treated developed rhabdomyolysis; two of the four had acute renal failure. Beginning in 1988, a second protocol--lovastatin at 20 mg/day as monotherapy--was used in patients who despite dietary intervention had total cholesterol greater than 240 mg/dl (mean follow-up 13 months). In the 15 patients so treated, mean total cholesterol decreased from 299 +/- 10 mg/dl before treatment with lovastatin to 235 +/- 9 mg/dl during treatment (21% reduction, p less than 0.001) and mean LDL cholesterol was reduced from a baseline value of 190 +/- 10 to 132 +/- 12 mg/dl during treatment (31% reduction, p less than 0.001). In this study, lovastatin at a dose of less than or equal to 20 mg/day as monotherapy was a well tolerated, effective treatment for hyperlipidemia after heart transplantation. It did not result in rhabdomyolysis and required no alteration in immunosuppressive therapy. However, the dose should not exceed 20 mg/day and combination therapy with either gemfibrozil or nicotinic acid should be avoided, even if the target LDL cholesterol value is not reached.

Teaching safety skills to high school students with moderate disabilities

Teaching students with disabilities to respond appropriately to potentially dangerous situations is a useful skill that has received little research attention. This investigation taught 3 students with moderate mental retardation to remove and discard broken materials (plates, glasses) safely from (a) a sink containing dishwater, (b) a countertop, and (c) a floor. A 4th student was instructed on the sink task only. A multicomponent treatment package was used to teach the skills. Simulated materials were used initially and were replaced with broken plates and glasses. A multiple probe design was used to evaluate the effectiveness of the treatment package. The results indicated that the treatment package was effective in teaching the skills. Data were collected 1 week and 1 month following the completion of training, and indicated mixed results. No student was injured during any phase of training. Issues pertinent to teaching safety skills to students with moderate disabilities are discussed.

Lipoprotein(a) and apolipoprotein changes after cardiac transplantation

Although lipoprotein changes after cardiac transplantation have been documented, the effects of transplantation and subsequent immunosuppressive therapy (particularly the combination of prednisone, azathioprine and cyclosporine) on apolipoprotein levels and lipoprotein(a) have not been reported. Fasting cholesterol, triglycerides, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, apolipoprotein A-1 and B-100 and lipoprotein(a) were evaluated in 69 consecutive patients during the waiting period before cardiac transplantation. There were 28 deaths before donor organ identification and 41 patients received a cardiac allograft. The lipoprotein levels of transplant recipients were again assayed 3 months postoperatively. Mean (+/- SEM) values increased for total plasma cholesterol (from 180 +/- 8 to 228 +/- 8 mg/dl, p less than or equal to 0.001), triglycerides (from 126 +/- 11 to 207 +/- 14 mg/dl; p less than or equal to 0.001), HDL cholesterol (from 39 +/- 2 to 49 +/- 3 mg/dl; p less than or equal to 0.002) and LDL cholesterol (from 119 +/- 7 to 138 +/- 7 mg/dl; p less than 0.02). Apolipoprotein A-1 and B-100 also increased, but lipoprotein(a) decreased from 11.7 +/- 1.7 to 6.8 +/- 1.1 mg/dl; p less than or equal to 0.0001) after transplantation. Although total cholesterol, triglycerides, LDL cholesterol, apolipoprotein A-1 and B-100 increased dramatically after cardiac transplantation, so did HDL cholesterol, thereby keeping the LDL/HDL cholesterol ratio constant. The surprising decrease in lipoprotein(a) after cardiac transplantation suggests that metabolism of lipoprotein(a) is independent of LDL cholesterol and that immunosuppressive drugs either decrease the synthesis or increase catabolism of lipoprotein(a).

Insensitivity of noninvasive tests to detect coronary artery vasculopathy after heart transplant

Obstructive coronary artery vasculopathy can be a major problem after cardiac transplant. The use of noninvasive tests to detect coronary artery vasculopathy was studied in 73 consecutive patients after heart transplant. Angiographically or autopsy-proved coronary artery disease was noted in 19 consecutive patients (26%) followed prospectively for 2.5 +/- 1.3 years (mean +/- standard deviation). Patients underwent yearly surveillance echocardiographic, rest/exercise-gated wall motion, oral dipyridamole thallium, ambulatory electrocardiographic monitor and angiographic studies. Positive test results were defined by decrease in ejection fraction, wall motion abnormality, failure to increase ejection fraction, lack of systolic blood pressure increase, and ischemic ST changes at maximal exercise (or on ambulatory monitor). Wall motion abnormalities and depressed ejection fraction on echocardiography were also abnormal studies as were fixed or reversible perfusion defects on thallium scan. Angiograms were considered positive when 50% luminal narrowing was observed and autopsy coronary artery vasculopathy was defined as cross-sectional coronary obstruction greater than or equal to 70%. No procedure that was examined proved to be a sensitive noninvasive detector of heart transplant coronary artery vasculopathy. All except ambulatory electrocardiographic monitoring had positive predictive values less than 50%. Interestingly, of the techniques evaluated, echocardiography was most sensitive (53%). The poor predictive ability of noninvasive testing in this population may be due to the fact that these tests are designed to detect effects of ischemia rather than coronary obstruction alone. Use of these particular noninvasive modalities routinely after heart transplant to detect coronary artery vasculopathy should be reconsidered because of their low sensitivity and predictive value when used as a surveillance screen.

Once-daily pravastatin in patients with primary hypercholesterolemia: a dose-response study

This multicenter, double-blind, placebo-controlled study was conducted to evaluate dose-response effects and safety of once-daily administration of pravastatin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. Pravastatin 5, 10, 20, 40 mg or placebo was administered at bedtime to 150 patients with primary hypercholesterolemia inadequately controlled on a low-fat, low-cholesterol (AHA Phase I) diet. After 8 weeks of treatment, pravastatin produced dose-dependent reductions in low-density lipoprotein (LDL) cholesterol of 19.2 to 34.1% (p less than or equal to .001 vs. baseline and placebo) and reductions in total cholesterol of 14.3 to 25.1% (p less than or equal to .01 to p less than or equal to .001 vs. placebo and p less than or equal to .001 vs. baseline). The relationship between the loge dose of pravastatin and decrease in LDL cholesterol was linear (p less than 0.002). High-density-lipoprotein cholesterol increased up to 11.7% and triglycerides decreased by as much as 23.9%. Pravastatin was well tolerated; no patient withdrew from the study as a consequence of treatment-related adverse events. Despite its relatively short serum half-life of approximately 2 h, once-daily administration of pravastatin provides a safe and effective means of reducing elevated LDL and total cholesterol.

Phrenic nerve pacing of the quadriplegic patient

Phrenic nerve pacing can be used to free a quadriplegic patient from ventilatory dependency. During a 6-year period (1982 to 1988), 23 patients with an age range of 17 to 63 years (mean 31 years) underwent implantation of a phrenic nerve pacemaker because of ventilatory dependency resulting from quadriplegia. Fourteen patients had a unilateral phrenic nerve implant and nine had a bilateral implant. The time from injury to implantation was 12 to 16 weeks. The site of implantation was the cervical phrenic nerve in 13 patients and the thoracic phrenic nerve in 10 patients. During the past 24 months, only a transthoracic approach has been used. The indication for pacing was failure to be weaned from ventilatory support in all patients. Failure to stimulate the phrenic nerve at implantation was noted in three patients, despite preoperative testing indicating an acceptable response. There were no deaths, and minor complications developed in three patients. Follow-up is available in all patients: Eight patients are completely free from the ventilator; nine patients are in markedly improved condition but require the ventilator at night; three patients are in moderately improved condition; and three patients had no response. Three patients required reexploration for component failure from 6 weeks to 18 months after implantation.

Association of levels of lipoprotein Lp(a), plasma lipids, and other lipoproteins with coronary artery disease documented by angiography

In a study of 307 white patients who underwent coronary angiography, the relationship of coronary artery disease (CAD) to plasma levels of lipoprotein Lp(a) and other lipid-lipoprotein variables was examined. Lp(a) resembles low-density lipoprotein (LDL) in several ways, but can be distinguished and quantified by electroimmunoassay. CAD was rated as present or absent and was also represented by a quantitative lesion score derived from estimates of stenosis in four major coronary vessels. Coronary lesion scores significantly correlated with Lp(a), total cholesterol, triglycerides, LDL cholesterol, and high-density lipoprotein (HDL) cholesterol levels by univariate statistical analysis. By multivariate analysis levels of Lp(a) were associated significantly and independently with the presence of CAD (p less than .02), and tended to correlate with lesion scores (p = .06). Among subgroups Lp(a) level was associated with CAD in women of all ages and in men 55 years old or younger. An apparent threshold for coronary risk occurred at Lp(a) lipoprotein mass concentrations of 30 to 40 mg/dl, corresponding to Lp(a) cholesterol concentrations of approximately 10 to 13 mg/dl. Plasma Lp(a) in white patients appears to be a major coronary risk factor with an importance approaching that of the level of LDL or HDL cholesterol.

Specialized delivery systems for intravenous nitroglycerin. Are they necessary?

Nitroglycerin is absorbed in vitro into polyvinyl chloride tubing, and it has been recommended that nitroglycerin be administered intravenously through specialized polyethylene infusion sets. To determine if tubing type is essential to achieve physiologic effectiveness, we studied dose responses to intravenous nitroglycerin in 15 patients with heart failure using standard polyvinyl chloride tubing in seven (group 2) and special polyethylene infusion sets in seven (group 1) (one patient was excluded from analysis because of technical difficulties). We monitored heart rate, blood pressure, right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output. Cardiac index, systemic and pulmonary vascular resistance, triple index, rate pressure product, stroke volume, stroke volume index, and stroke work index were calculated. Baseline and treatment measurements were obtained from five to 15 minutes after the infusion of 10, 20, 40, and 80 micrograms of nitroglycerin per minute. Over-all, systolic blood pressure decreased (p less than 0.05) about 8 percent and mean blood pressure approximately 12 percent, mean pulmonary artery pressure and mean pulmonary capillary wedge pressure decreased 30 to 40 percent, and the decline in mean right atrial pressure was 35 percent of baseline (all p less than 0.05). Heart rate and cardiac index did not change (p greater than 0.05). Pulmonary vascular resistance decreased slightly (p = 0.07) and systemic vascular resistance significantly (p less than 0.05). When the two groups were compared physiologic changes were virtually identical (p less than 0.05). Two-way analysis of variance for baseline corrected data proved no differences between tubing sets (p less than 0.05), but the infusion concentration rate was highly related to response (p = 0.0001). A significant (p less than 0.05) decrease in mean blood pressure and mean right atrial pressure was noted at lower dose rates (20 micrograms per minute and 40 micrograms per minute, respectively) in group 1. Beneficial hemodynamic effects in heart failure patients can, then, be predicted to occur at 80 micrograms per minute infusion rates; these responses seem independent of the type of infusion tubing system employed. Additionally, when patients given intravenous nitroglycerin for various reasons were followed for 48 hours, the majority receiving infusions via polyvinyl chloride tubing (group 2) did not require dosage adjustments. Also, at lower flow rates, more solution than calculated may be delivered when polyethylene tubing infusion sets are employed with volumetric infusion pumps.